1. Field of the Invention
The invention relates to an electric motor, and more particularly, to an electric motor having a heat pipe.
2. Description of the Related Art
In each of Taiwanese Utility Model Nos. M331251, M322677 and M300395, and Taiwanese Patent No. I250718, an electric motor is disclosed, which utilizes a fan impeller driven by a rotor shaft to thereby generate cooled air flow for heat dissipation. The cooled air flow generated by the fan impeller passes through the interior of a rotor of the motor. As a result, the fan impeller provides an inferior cooling effect when the interior of the rotor contains too much dirt.
Another conventional electric motor disclosed in U.S. Pat. No. 4,406,959 includes a heat pipe formed in a rotor shaft and extending along a central axis of the rotor shaft. Due to the presence of the heat pipe, the rigidity of the rotor shaft is reduced, thereby reducing a torsional force provided by the motor. Furthermore, heat from the periphery of the rotor is transmitted to the heat pipe through relatively long heat-conduction paths, thereby resulting in an inferior heat dissipation effect. Thus, for an electric motor having small size and high power, heat accumulation may result in demagnetization of laminating members of the rotor.